Citrus oils aldehyde content

The oils have a high terpene hydrocarbon content (>90%, mainly (+)-limonene), but their content of oxygen-containing compounds differs and affects their quality. Important for aroma are aldehydes, mainly decanal and citral, and aliphatic and terpenoid esters. The sesquiterpene aldehydes a-sinensal [17909-77-2] and/3-sinensal [6066-88-8], which contribute particularly to the special sweet orange aroma, also occur in other citrus oils, although in lower concentration [369-370a, 370d, 394,421, 430-438]. 

Pineapple oil, peel-oil content and aldehyde composition, see also Citrus oils Pin milling, starch isolation, 673, 677 Pipetting technique, 754-755 PL. see Pectic lyase... 

Support Protocol 1 Determination of Moisture Content Basic Protocol 8 Quantification of Total Aldehydes in Citrus Oils by Gl.5.10... 

Aldehyde content is considered an important flavor note included in the standard of identities for citrus oils. The flavor strength of an oil is based on the aldehyde content, where higher is better. The two major aldehydes are acetaldehyde and octanal. The quantification of aldehydes is based on the reaction of citral in the sample with a hydroxylamine solution, followed by titration with KOH in the presence of ethyl orange indicator. It is modified from AOAC Method 955.32 (AOAC, 1990c Redd et al., 1986). This method was originally developed for lemon oils however, it is applicable to other citrus oils. 

Properties of essential oils depend on citrus fruit and variety, in an extraction oil-dependent manner. The differences in some of their properties can be observed in Table 5.4. The aldehyde content in lemon and lime cold-pressed oils is considerably higher than in orange oil but is close to the content of grapefruit distilled oil (Food Chemical Codex, 1996). The variations in aldehyde content are related to the... 

The flavour properties of the citrus oils are based on compounds like aldehydes, esters and alcohols. Aldehydes play the most important role in citrus flavours. Mainly the saturated C-8, C-10 and C-12 long-chain constituents as well as the terpenoid aldehydes citral (a mixture of neral and geranial) and citronellal form the basic notes of the fresh and pleasant citms flavour. Also sesquiterpene aldehydes and ketones, such as sinensal or nootkatone, are significant for citms flavours. The aldehyde content, therefore, is frequently used as a quality criterion for citms oils. Important citms alcohols are linalool, octanol, a-terpineol (especially in distilled lime oil) and ter-pinen-4-ol. Furthermore, esters contribute to the flavour properties of citms oils. Especially the acetates of geraniol and nerol and, to a lesser extent, citronellol are... 

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